#1
Hi,

I have a Laney RB4 amp - unfortunately, it had a drink split into whist it was being used.

It blew the 2 fuses inside and after replacing them and cleaning, it now blows them everytime the amp is switched on. Is there a way i can find where the short is and how can test components to check they`re ok?

thanks,
mike
#2
You probably fried it. If it wasnt powered up and got wet you could dry it out probably not have any problems. But as it was powered up it most likely fried an IC inside. You might be able to take it apart and clean it up dry it out good and maybe it will work but. But most likely your gonna be buying a new amp its hard to look at a IC and see its bad it would have to be tested. Which means removing it which is a good way of screwing it up to. You have learned a lesson that amps arent tables.
#3
Quote by Tackleberry
You probably fried it. If it wasnt powered up and got wet you could dry it out probably not have any problems. But as it was powered up it most likely fried an IC inside. You might be able to take it apart and clean it up dry it out good and maybe it will work but. But most likely your gonna be buying a new amp its hard to look at a IC and see its bad it would have to be tested. Which means removing it which is a good way of screwing it up to. You have learned a lesson that amps arent tables.


It's too true, I'm afraid.

*removes glass of water, empty plate, numerous sheets of paper and Primark bag*
#4
it wasn`t my drink - i did`nt know it was being used as a table

i did have it looked at by the studio where we practice and he confirmed that the 4 large transistors (can`t remember the technical name) had blown - these were replaced. When it was switched back on it worked for about 2-3 mins and then it blew the 2 fuses again. Apparantly sugar (it was cider) conducts electricity a bit and this has probably caused it to go again.

I`m gogin to clean the pcb with isopropyl alcohol and see how it goes when it switches back on - if they blow again, whats the best way to track down where the problem is - i have to admit, i really can`t afford to bin an amp because it keeps shortings.

thanks, mike
#5
the best thing to do would be to take it to a tech, preferably one who specializes in Laneys.
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#6
You need to wash all the sugar and such off the board, trick will be getting it out from under the ICs. And if it fried transistors it probably took some ICs with it to. Getting SS stuff fixed can be a frustrating and expensive process. Its why not much SS gets fixed. You could very well spend the same amount of money getting it diagnosed and fixed as a new amp will cost.
#7
well, i washed the pcb in isopropyl alcohol - while i was doing this, i noticed that a couple of solders which connect some diodes in series looked a little burntish. i removed the 3 diodes from the pcb and it looks like one of these is letting current flow both ways.

i`ve managed to source some new ones on the interent so they`re arriving tomorrow and i can fit them and retest again. at the very least, the pcb needed cleaning badly and the diodes needed replacing.

i`ll see what happens next..